code: def test_categorical_positions_horizontal(self):
      x = [1, 2]
      y = ["a", "b"]
      w = 0.8
      bars = self.plot_bars({"x": x, "y": y}, {}, {})
      for i, bar in enumerate(bars):
          self.check_bar(bar, 0, i - w / 2, x[i], w)
  
imports: import numpy
  import pandas
  from matplotlib.colors import to_rgba, to_rgba_array
  import pytest
  from numpy.testing import assert_array_equal
  from seaborn._core.plot import Plot
  from seaborn._marks.bar import Bar, Bars
label_desc: Use image node_id 4 for calling the TestBar obj's underlying member method code with example usage: obj.test_categorical_positions_horizontal() without return types